Disk unit with a side mounted board

ABSTRACT

In a disk unit containing in a predesignated size, an arm, read/write heads secured to an end of arm, a printed circuit board, and leads connecting read/write heads to the printed circuit board, the disk unit of the present invention is realized by: 
     employing a straight-type arm in place of a conventional dog-leg shaped arm; 
     providing a structure for mounting a printed circuit board on a side of the disk unit where a space is made by employing the straight-type arm; 
     moving a printed circuit board conventionally mounted above the disks to the above-mentioned space, thus evacuating the upper part of the disks; and 
     providing additional disks in the above-mentioned evacuated upper part of the disks to increase storage capacity of a disk unit.

This application is a continuation of application Ser. No. 520,412,filed May 8, 1990, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a disk unit, and more particularly to amagnetic disk unit used for an auxiliary storage of a computing system.

Recently, with the remarkable development of a computing system, moreand more reliable, large-capacity and small-sized magnetic disk unit isbeing demanded.

2. Description of the Related Art

FIG. 1 is a perspective view of a magnetic disk unit of a related art,whose structures are disclosed in U.S. Pat. No. 4,899,237. A pluralityof disks rotated by a not-depicted spindle are on the A side, and apositioner for positioning read/write heads is on the B side. Connector92 leads disk read/write signals to/from not-depicted read/write heads.First printed circuit board (called PCA hereafter) 41, which is forcontrolling disk read/write operation, is mounted on the upper side ofthe unit with spacer tubes 44 between and has its connector 95 matedwith connector 92. Third PCA 42, which is also for controlling diskread/write operation, is mounted on the rear side and is connected tofirst PCA 41 via their connectors (not depicted in the figure). SecondPCA 43 is for controlling disk read/write and positioning operationaccording to the commands sent from a not-depicted disk controller viainterface connector 35. Second PCA 43 is secured to metal fittings 48,49 to mount on top of the unit and connected to first PCA 41 viaconnectors 93, 94 and cables 46. Plates 66 with rubber vibrationisolator mounts the unit on a not-depicted cabinet.

A magnetic disk unit with, for example, 8-inch disks is generallypredetermined to be up to 216 mm(W)×127 mm(H)×380 mm(D) in dimensions toaccommodate the unit in a standard cabinet. In the prior structure,however, there was no space for additional disks to increase storagecapacity because of the limitation of height. Therefore, a problem isthat in spite of an ever-increasing demand for a large-capacity magneticdisk unit, there was no means to satisfy the demand without increasingthe size and deteriorating reliability.

SUMMARY OF THE INVENTION

An object of the present invention is to increase the storage capacityof a disk unit by increasing the number of disks within a disk unit of apredetermined size.

Another object of the present invention is to improve the reliability ofa disk unit.

The first object is accomplished by employing a straight-type arm inplace of a conventional dog-leg shaped arm, and moving a printed circuitboard to a space vacated by employing the straight-type arm.Furthermore, by providing a bending metal to guide leads carrying diskread/write signals to/from the heads, the second object is accomplished.

The present invention has applied a straight-type arm to a disk unitdesigned conventionally with a dog-leg shaped arm because astraight-type arm swings over a smaller area than a dog-leg shaped arm.

The present invention has depressed a part of the base (which houses thedisk unit proper) in a space where the straight-type arm does not swing,provided a structure for mounting a printed circuit board in thedepressed portion, and moved therein a printed circuit boardconventionally mounted above the disks. Thus, a space is provided in thedirection of height, permitting addition of disks to increase storagecapacity.

The present invention has also provided a bending metal as a means todivert the route of the leads carrying disk read/write signals to/fromthe heads so that it may not touch other parts of the disk unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a magnetic disk unit for illustratingthe structure of a related art of the present invention;

FIG. 2 is a perspective view of a magnetic disk unit embodying thepresent invention;

FIG. 3 is a sectional view of a magnetic disk unit embodying the presentinvention;

FIG. 4 is a top plan view of the positioner of the present invention;

FIG. 5 is a diagramatic top plan view showing the positioner of thepresent invention;

FIG. 6 is a side elevational view of the positioner of the presentinvention;

FIG. 7 is an exploded view of a bending metal;

FIG. 8(a) shows a plate for securing a printed circuit board to the baseand FIG. 8(b) shows a side view of FIG. 8(a); and

FIG. 9 shows a window cover.

Throughout the above-mentioned drawings, identical reference numeralsdesignate the same or similar component parts.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 2 shows the structure of a magnetic disk unit of the presentinvention.

A plurality of magnetic disks 2 rotated by spindle motor 19 (See FIG.3.) are on the A side, and a positioner for positioning heads 9 is onthe B side.

First, the present invention has depressed a part of base 1 (depicted byD in FIGS. 2, 4 and 5) in a space evacuated by employing a straight-typearm (which is constructed such that arm 5 and spring arm 5s (See FIG. 4)supporting read/write heads are oriented lengthwise substantially in thesame direction. See, for example, U.S. Pat. No. 4,620,251.) in place ofa conventional dog-leg shaped arm. Second, it has heightened base 1.Third, it has provided a structure for mounting a printed circuit board(112 mm(W)×108 mm(H)×10 mm(D)) in the depressed portion D. (Fordimensions, see FIG. 4.) This has been realized because, as shown inFIG. 4, straight-type arm swings over the area from the broken-line armposition to a little inner position of that of the solid line, and alarge-capacity magnetic disk unit (216 mm(W)×127 mm(H)×380 mm(D)) having8 disks as shown in FIG. 1 has height enough to house a printed circuitboard of above-mentioned size. Second PCA 33 mounts an interface circuitfor receiving and sending commands and disk read/write data to/from anot-depicted disk controller via connector 35. Second PCA 33 also mountscircuits for controlling currents flowing through the voice coil woundon bobbin 4 which is secured to arm 5, according to the difference ofthe current arm position from the desired position so that heads 9 canbe positioned on a desired disk track. First and third PCAs 31, 32 mountcircuits for wave-shaping, amplifying and demodulating read signals fromheads 9 and for modulating write signals to heads 9. Third PCA 32, whichis mounted on the rear side of the unit as was conventional PCA 42, isconnected to second PCA 33 via their connectors (not depicted in thefigure).

The functions of conventional first PCA 41 has been distributed to PCAs31, 32 and 33 to exclude conventionally-needed first PCA 41.Newly-provided first PCA 31, which has above-mentioned functions, hasbeen mounted in depressed portion D because portion D is located closeto read/write heads.

With reference to FIG. 3, PCA 33 is placed on top of the unit with partsside down, and particularly with taller parts 33t mounted in deepportions of base 1 while shorter parts 33s in shallow portions (or inthe center of PCA 33) to make base 1 as high as possible within alimited height. Thus, the present invention has made it possible to adddisks to increase storage capacity. When applied to a disk unit having 8disks as shown in FIG. 1, in addition to the improvement to reduce thepitch disks are disposed with, the present invention permits to add 4more disks to total 12 disks as shown in FIG. 3.

With reference to FIGS. 4 and 5 which show the structure of thepositioner part of the magnetic disk shown in FIG. 2.

Base 1 (hatched in FIG. 4) houses the mechanical and electronic partsconstituting a magnetic disk unit, such as magnetic disks 2, arm 5,heads 9, and magnetic circuit 3 having permanent magnets 41 (See FIG.6.) and voice coil-wound bobbin 4. Arm 5 has heads 9 at first end Eland, at second end E2, bearing 7 and bobbin 4. Bobbin 4 is connected toarm 5, reinforced by ribs 8, and supported rotatably on rotationalmember 6 by bearing 7. When a current flows through the voice coil (notdepicted in the figure) wound on bobbin 4, bobbin 4 moves horizontally(e.g. clockwise) about the axis of rotational member 6, and arm 5 in theopposite direction (e.g. counterclockwise), thus positioning heads 9 ona desired track.

A magnetic disk unit with 22 disk surfaces on 12 disks as shown in FIG.6, requires 1 head per disk surface, a total of 22 heads. Therefore,head ICs (integrated circuits for amplifying read/write signals to/fromheads 9) are needed corresponding to the number of heads. Moreover, thehead ICs must be placed as close to heads 9 as possible to minimize thecapacitance, inductance and resistance offered by wiring. Hence,flexible printed circuit board (called FPC hereafter) 10 is utilized tomount the head ICs and to carry disk read/write signals and power forthe voice coil on bobbin 4 to/from terminal 11, which is mated withconnector 16 to connect newly-provided first PCA 31. (See FIG. 4.) Asshown in FIG. 5, FPC 10 consists of three parts: parts F and G, bothstuck to arm 5, and part H. Part F is divided into as many portions asthe number of heads 9 with its tips soldered (solder 12) to first end E1of arm 9 to wire between heads 9 and the head ICs. Part G mounts headICs. Part H is divided into three portions P, Q and R at second end E2of arm 5 and leads to terminal 11. Portion Q carries power for the voicecoil; and portions P, R carry disk read signals to second PCA 33 viaterminals 11 and 16, first PCA 31, and connectors 34 and 25; and diskwrite signals in the reverse order. Part H (portions P, Q, R) of FPC 10needs slack enough to allow arm 5 to move freely over disks 2. However,a problem is that, as a result of depressing base 1 (depressed portionD), terminal 11 has come near to magnetic circuit 3, which causes FPC 10(part H) to rub against magnetic circuit 3, damaging each other andproducing dust and powder.

As shown in FIGS. 4 and 5, the present invention overcomes the problemby attaching bending metals 15 at second end E2 of arm 5 and therebydiverting the FPC's route to terminal 11 to prevent FPC 10 from touchingmagnetic circuit 3.

FIG. 7 illustrates an example of the structure of above-mentionedbending metal 15 in more detail. Bending metal 15 consists of L-shapedmetal fitting 57, plate 58 which presses FPC 10 against metal fitting57, and pin 59 which locks plate 58 to metal fitting 57. Metal fitting57 has holes 56 on one side of the metal bent in an acute angle andholes 51 on the other side. Holes 56 are for securing metal fitting 57and FPC 10 to arm 5. Holes 51 are for inserting pin 59 to fasten FPC 10between metal fitting 57 and plate 58. In FIG. 6, a single pin 59 lockstwo sets of plate 58 and metal fitting 57 to fasten portions P and R incommon. When secured to bending metal 15, FPC 10 takes its route apartfrom magnetic circuit 3 to terminals 11, thus preventing FPC 10 fromtouching magnetic circuit 3 in seek modes in which arm 5 swings overmagnetic disks 2 to selectively position heads 9, and thereforepreventing production of dust and powder and disconnection of the signallines in FPC 10.

In FIGS. 4 and 5, portions P and R of FPC 10 are guided by bendingmetals 15 which is illustrated in FIG. 7 in detail; and portion Q isguided by another bending metal of a similar type.

FIG. 8(a) shows plate 70 for securing first PCA 31 to base 1. FIG. 8(b)is a side view of FIG. 8(a), viewed from arrow A. Plate 70 is screwed tofirst PCA 31 through holes 72. In FIG. 2, first PCA 31 is screwed(screws 23) to base 1 through holes 71 of plate 70 and holes 22 ofbase 1. On mounting second PCA 33 on the upper side of the unit byscrewing (screws 26) to spacer tubes 64, its connector 25 is mated withconnector 34 of first PCA 31 to connect signal lines of both PCAs.

With cover 80 (See FIG. 9.) attached by screwing, window 67 protectsfirst PCA 31 from dust. With cover 80 detached, window 67 allows thewaveforms of disk read/write signals to be observed while the unit isoperating with first PCA 31 mounted on the unit. As shown in FIG. 2,three holes 60a, 60b and 60c are provided in base 1 to let the air froma not-depicted fan flows through. (In FIG. 2, only air flow through hole60c is shown by an arrow.) Since first PCA 31 is disposed vertically inparallel with the axis of rotational member 6 or with the side of theunit, air coming from the three holes flows through between first PCA 31and cover 80 to second PCA 32 to cool both PCAs uniformly.

Thus, a printed circuit board which were mounted conventionally on theupper side of the unit (i.e. above disks 2) has been moved to the sideof the unit. As a result, an empty space of approx. 10 mm in height hasbeen provided above the disks, allowing an addition of 4 more disks to aconventional magnetic disk unit with, for example, 8-inch disks.

What is claimed is:
 1. A disk unit comprising:a disk having a rotationalaxis thereof; a read/write head, positioned onto said disk, for readinginformation out and/or writing information on said disk; an arm,connected to said read/write head, for positioning said read/write headonto a desired position of said disk; a housing having a wall providedin parallel with the rotational axis of said disk, the wall having adepressed portion; and a printed circuit board, connected to saidread/write head and located in the depressed portion, said printedcircuit board extending in parallel with the rotational axis of saiddisk.
 2. A disk unit according to claim 1, further comprising:a leadconnecting said read/write head to said printed circuit board; anddiverting means, provided on said arm, for changing a route said leadfollows so that said lead is kept away from parts of said disk unit. 3.A disk unit according to any one of claim 1 or 2, wherein said depressedportion is provided in a space outside an area where said arm swings. 4.A disk unit according to claim 2, wherein said diverting means is anL-shaped metal fitting.
 5. A disk unit according to claim 1 wherein saidprinted circuit board mounts circuits which receive and send read/writesignals from/to the read/write head.
 6. A disk unit comprising:aplurality of disks having a rotational axis thereof; a plurality ofread/write heads, positioned onto said disks, for reading informationout and/or writing information on said disks; a straight-type armconnected to said read/write heads, for positioning said read/writeheads onto a desired position of said disks; a housing having a wallprovided in parallel with the rotational axis of said disks, the wallhaving a depressed portion; and a printed circuit board, connected tosaid read/write heads and located in the depressed portion, said printedcircuit board extending in parallel with the rotational axis of saiddisks.
 7. A disk unit according to claim 6, wherein said depressedportion is formed inward from the wall of said housing.
 8. A disk unitaccording to claim 6 wherein said printed circuit board mounts circuitswhich receive and send read/write signals from/to the read/write head.